Mast locking mechanism

ABSTRACT

A mechanism for locking a tiltable mast and a machinery platform of a drilling apparatus together includes a tapered latch pivotable into and out of complementary wedging relationship with a tapered slot formed in a catch at the foot of the mast. The tapered latch is secured on a pivoted shaft, and a hydraulic actuator provides an operating force for rotating the shaft to move the tapered latch into and out of engagement with the tapered slot of the catch.

United States Patent 1191 Nelmark et al.

1451 Sept. 16, 1975 1 MAST LOCKING MECHANISM 3,212,593 10/1965 Reischl 175/85 3,245,180 41966 B l t 11.. 52 116 1751 Inventors: Jack D New Bern; 3 250401 5/1966 :171:56: 1 52 12 7 x Matthew Smith Milwaukee both of 3:778:9 12 1973 Blecken 52/116 Wis. FOREIGN PATENTS OR APPLICATIONS 1731 Asslgnee- 3 9 fF: South 893,394 9/1953 Germany 52 120 880,997 4/1943 France 52/116 [22] Filed: Mar. 2 1974 1,335,972 7/1963 France 52/753 G 1211 Appl Primary Examiner-Ernest R. Purser Assistant Examiner-Leslie A. Braun 52 us. Cl. 52/116; 52/753 0; 173/28; Attorney, Agent, or FirmQuarles & Brady 173/42; 248/2 [51] Int. Cl. E04H 12/34 [57] ABSTRACT [58] Field of Search 52/116-120, A mechanismfor ocking a tumble mast and a machin 52/753 248/2 173/28 43 ery platform of a drilling apparatus together includes a tapered latch pivotable into and out of complementary [561 References C'ted wedging relationship with a tapered slot formed in a UNITED STATES PATENTS catch at the foot of the mast. The tapered latch is se- 301,019 6/1884 Teal 52/1 13 cured on a pivoted shaft, and a hydraulic actuator pro- 2,336,432 12/1943 Wilson... 52/1 18 X vides an operating force for rotating the shaft to move 2.496.706 1950 Ficdler-v- 173/28 the tapered latch into and out of engagement with the 2,703,634 3 1955 Lee 52 119 x tapered Slot of the Catch 2,993,570 7/1961 Bender 52/120 X 3,032,147 /1962 Wilkinson et a1. 52/118 3 Claims, 4 Drawing Figures 1 :L:1I 711 I I I 3'32;- 1 5 Z6 5 :HZ'TI f L". ::;2 O 111'? H L/ /a x4 3 l I I i l I 1 \QL- 1 -n 11 SHEET 1 OF 3 PATENTEB sw 1 6 i975 PATENTEB SEPI 61975 SHEET 2 BF 3 PATENTEBSEP I 61975 .KET 3 [IF 3 MAST LOCKING MECHANISM BACKGROUND OF THE INVENTION The invention relates to rotary drilling apparatus and more particularly to a locking mechanism for tightly securing a mast ofa blast hole drill in an upright, or angular, drilling position to the machinery platform without losseness or play. While the preferred embodiment is especially useful in stabilizing the mast of a rotary blast hole drill, the invention is nevertheless not restricted exclusively to this field, and it may be applied wherever it is desirable to firmly maintain the position of pivotable masts, towers, derricks or similar structures.

Conventional blast hole drilling equipment includes a carrier vehicle with a main frame, or machinery platform, upon which a mast is pivotably mounted for movement between a horizontal transport position and a raised upright, or angular, drilling position. Before actual drilling is initiated, it is necessary that the base of the raised mast be firmly secured in fixed relation to the machinery platform in order to withstand the severe operating forces without collapse, or other distortion of the mast. Also power units and control apparatus on the machinery platform are coupled to a drill string head and drive chain on the mast, and this coupling requires a steady mast position.

In the prior art, coupling of the mast with the machinery platform has been accomplished, subsequent to a raising of the mast, by aligning openings formed in the mast and the machinery platform, and then driving pins into the openings to effect a connection. A mast locking arrangement of this character is disclosed in U.S. Pat. No. 3,212,593 issued to K. E. Reischl on Oct. 19, 1965. In that patent, the foot of the tiltable mast is provided with a series of circular openings which are brought into alignment with other circular openings formed in an arcuate sector attached to the machinery platform of the main frame. Pins are then introduced through the openings to secure the mast in place.

Other similar pinned mountings for the mast of a drilling rig are shown in US. Pat. No. 3,245,180 issued to H. L. Bules et al. on Apr. 12, 1966 and US. Pat. No. 3,695,363 issued to J. L. Kelly Jr. on Oct. 3, 1972. Both of these constructions feature a hydraulically raised and lowered tiltable mast together with adjustable brace legs for holding the mast in position. These adjustable legs utilize transverse retainer pins inserted in appropriate openings, and in Kelly Jr. the adjustable brace legs are in the form of jack screws associated with an arcuate sector on the mast that has a series of pin receiving openings. These constructions are similar to Reischl in the concept of using ordinary pinned connections for holding the mast in an upright drilling position.

Utilization of such pinned connections for locking a mast in an operative drilling position creates a number of problems. For example, the pins usually have some degree of clearance with respect to the walls of the apertures in which they reside, such that vibration and chatter caused by drilling develops circumferential grooves in the pins which loosen the connection between the mast and the machinery platform of the blast hole drill. Compounding this defect is the fact that the mast is equally susceptible to vibrations which occur at the pinned connections about which the mast tilts. As a result, those vibrations occurring in the mast due to rotation of the drill string and the drilling action create torsional and gyrational stresses and produce mechanical fatigue leading to deterioration of the mast. Also, the mast is subject to resonant frequencies encountered in drilling for which amplification of the vibrations between the mast and machinery platform may occur. This increases maintenance requirements because of increased wear and fatigue. 1

Another drawback with pinned mast connections of the prior art is the difficulty associated with removing the pins from the openings, when it is desired to pivot the mast to an alternative drilling position, or to a prone transport position. Because of the circumferential grooves created in the pins by vibration, they cannot easily be driven out of their openings, and must often be removed using auxiliary power means. Since some on site operations necessitate frequent repositioning of the mast, it is essential to reduce time expended in removal of pins, when unlocking the mast to shift its position with respect to the machinery platform.

Some mast constructions have utilized wedging components to hold one section of mast in assembly with another section. In US. Pat. No. 2,583,072 issued to J. H. Wilson on Jan. 22, 1952 there is shown the use of cam-shaped locking pins. This device, used in connecting sections of a derrick mast one above the other, features a pin having a cam-shaped member which is rotatively wedged into a flange lock on the mast and held in position by gravity, by virtue of a weighted handle on the cam-shaped member. In Davidson, US. Pat. No. 3,250,401 issued May 19, 1966 the mast sections of a tower crane are connected with one another by wedging parts of one into the other, and then holding the parts in assembly by pins inserted in ordinary circular openings. There is no constant application of a force against the wedged connections. Thus, this prior art doesnt utilize a wedge to hold a mast, or a part of a mast in tight, play-free, union with another part of the structure. Further, there is no recognition of overcoming problems of vibration from drilling by holding a mast securely to a platform in this prior art.

It is against this background of the art, in which tiltable masts are pin connectedin position, in such manner that there is play with respect to the machinery platform, that the present invention has been conceived.

SUMMARY OF THE INVENTION The present invention relates to a mechanism for tightly locking together, without play, a tiltable mast and a machinery platform of a drilling apparatus, and it more specifically resides in a catch member and a latch member engageable and disengageablein wedging relationship with one another. One of the members is on the mast and the other is associated with the machinery platform, and an actuator drives the latch into the catch with a wedge fit that affixes the mast in position without play with respect to the platform.

It is a general object of the invention to provide a positive lock of the mast of a blast hole drill with the machinery platform of the drill in a manner such that there is no loose connection between these elements. In preferred form, this goal is achieved by utilizing a unique latch and catch mechanism in which a tapered latch pivotably mounted on the machinery platform is tightly wedged into a mating tapered slot of a catch plate extending from the foot of the mast. As a result of this wedging connection, chatter in the mast induced by drilling action is vastly decreased from prior constructions using loose'pinned connections. By tightly clamping the mast to the platform a unitary whole is created to present a larger integral mass in the drilling machine that becomes available to dampen vibrations. As a result, fatigue and wear of the mast are markedly reduced, thereby extending its life.

The entire mass of a blast hole drill, which may inelude as much as 150 tons of machinery, is made available for dampening the vibrations, whereas in the prior art the pinned connections permitted the mast to vibrate independently of the platform, so that two separate masses vibrated which had different resonant frequencies. The inherent'frequency of the combination of the drill mast and the machine proper is less than for the mast alone, when it is loosely pinned to the frame and consequently resonant frequencies can be shifted to lower values which are less likely to occur. Further, the enhanced dampening of the larger, coherent mass reduces vibration.

Another advantage resides in the continuous, locking behavior of the mechanism which precludes disengagement of the locking components during drilling operations. Such advantage is obtained through the employment of a hydraulic actuator mounted in such manner that upon a downstroke of its piston rod there is a'utilization of the force of gravity, as well as hydraulic pressure, to hold the tapered latch within the tapered slot of the catch plate. This structure not only enhances the reliability of the device, by ensuring uninterrupted union of the mast and machinery platform, but also provides an automatic operation such that labor costs and related maintenance expenditures are significantly lessened. In addition, due to elimination of manual handling of locking pin elements, there is an improvement in the safety factors accompanying mast setup.

It is a further object to reduce vibrations which occur in a pivoted connection between a mast and its machinery platform. This is accomplished by providing that the engaging motion of the tapered latch and the tapered slot of the catch plate imparted by the downstroke of the hydraulic actuator is in a direction transverse to the axis of the pivoted connection. The engaging motion of the latch and catch elements produces a vertical force component which acts directly upon the pivoted connection and prevents chatter during drilling operations.

The foregoing and other objects and advantages of the invention will appear from the following description. In the description reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration and not of limitation a preferred embodiment of the invention. Such embodiment does not represent the full scope of the invention, but rather the invention may be employed in many different embodiments, and reference is made to the claims for interpreting the breadth of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view in elevation of a rotary blast hole drill incorporating a mast locking mechanism embodying the present invention, in which view parts have been broken away to show the foot of themast,

FIG. 2 is an enlarged fragmentary view of the right hand side of the mast foot as seen from inside the mast to show the mast locking mechanism located on that side,

FIG. 3 is an enlarged, fragmentary front view of the mast locking mechanism shown in FIG. 2, and

FIG. 4 is a fragmentary view of a modification of the mast locking mechanism applicable for angular drilling.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a rotary blast hole drill includes a machinery platform I mounted on crawlers 2 suitable for transporting the drill from one site to another. An operators cab 3 is situated along the forward portion of the left hand side of the machinery platform 1, and a machinery housing 4 is located rearwardly of the cab 3. A pair of mast supports 5 (only a top portion of one being shown) project upwardly from the front portion of the machinery platform 1 and serve as mounting posts to which a drilling mast 6 is pivotally secured by a transverse pivot shaft 7. The mast 6 is tiltable between a prone transport position (shown by phantom lines) and an upright drilling position, and is hoisted and lowered by telescopic ram means 8' secured between the mast 6 and the machinery platform 1. The mast 6 is supported for drilling by a collapsible back brace arrangement 1 1, and a conventional rotary head drilling mechanism 9 to which is coupled a drill string 10 is slidably mounted for movement along the length of the mast 6.

The machinery platform 1 and the mast 6 are positively secured together by a pair of mast locking mechanisms, one at each side of the mast foot. In FIGS. 13 the right hand side mechanism is generally identified by the numeral 12, such right hand side being that to the operators right when looking forward from the cab 3. The mast locking mechanisms function to effect and maintain a tight union of the mast 6 and machinery platform 1 without play between these-parts. The present invention resides in the structure of this arrangement, and for purposes of discussion only the locking mechanism 12 situated on the right hand side of the drill mast will be described, it being understood that the elements of the locking mechanism on the left hand side are the mirror image of that on the right, and that they operate in like manner.

Referring now to FIGS. 2 and 3, the bottom, or foot, of the tiltable mast 6 includes angular lattice elements 13, 14 and 15 which form part of a strengthening network for the lower portion of the mast 6. A catch plate 16 at the very end of the mast foot is welded to the bottom of the lattice element 15 and to the lower end of a mast upright 17. The catch plate 16 is provided with a tapered slot 18 that enters upwardly from the bottom thereof to serve as a catch for a latch arrangement to be described.

The machinery platform 1 extends in a horizontal plane and has a top, or deck 19 and a bottom 20 connected together, inter alia, by a vertical wall 21, as identified in FIG. 2. A hollow rectangular crossbeam 22 lies transverse to the vertical wall 21 and functions to interconnect the left and right hand sections of the platform 1. Extending vertically between the deck 19 and the bottom 20 of the machinery platform 1 is a mounting plate 24 extending as a forward continuation of the vertical wall 21. An inverted L-shaped suspending bracket 25 is firmly welded to the outside of the this point of connection between the mast 6 and machinery platform 1. an incident ofdeveloping a Y wedging fit of thelatch andcatch eleinents in which a As best depicted in'FlG. 2, a 'forward' bearing block 28 is welded to the front edges of the top plate 27 and the platform bottom 20. The lower end of this block 28 depends from the bottom to present a bearing opening 23, and a second bearing block 29 welded to the underside of the bottom 20 is spaced rearwardly from the block 28 with a bearing opening 32 aligned with the opening 23. A pivot pin 31 is borne by and extends between the bearing blocks 28, 29, and a pivot tube 30 is disposed on the pivot pin 31 for turning movement between the bearing blocks 28, 29.

A crank arm 33 has one end welded to the periphery of the pivot tube 30, and the other end is fixed to a piston rod 34 of a vertically disposed hydraulic actuating cylinder 35 whose casing end 36 is pinned to the upper end of the bracket 25. Also welded to the periphery of the pivot tube 30, but spaced axially of the crank arm 33, is a tapered latch 37 having an oblique face 38 disposed at an angle which will wedge into the tapered slot 18 of the catch plate 16. In FIGS. 2 and 3 the latch 37 is shown in a downwardly hanging, open position with respect to the catch slot 18, and in phantom in FIG. 3 it is depicted in a raised, latched condition.

In operation, the mast 6 is tilted about the pivot shaft 7 from a horizontal transport position to an upright drilling position, at which stage the tapered latch 37 associated with the machinery platform 1 is aligned with the tapered slot 18 of the catch plate 16. As shown. in FIG. 3, the hydraulic actuating cylinder 35 is operated by a pump 39 which forces hydraulic fluid in a reservoir 40 through a directional control valve 41 and two bydraulic feed lines, 42, 43 leading to the casing and rod ends of the cylinder 35. The directional control valve is of the three position type and includes means for lowering, raising and locking the piston rod 34 of the cylinder 35 in place as desired. The control valve 41 is initially set in a right hand position in which the piston rod 34 of the cylinder 35 is retracted, and the tapered latch 37 on the pivot tube 30 is thus disengaged from the tapered slot 18 of the catch plate 16. Shifting the valve 41 to its central position, the cylinder 35 is effectively pressurized to cause the piston rod 34 to move in a vertical downstroke and turn the tapered latch 37 on the pivot tube 30 upwardly into a wedging insertion with the tapered slot 18, as shown in phantom lines. The control valve 41 is finally shifted to its left hand position which shuts off fluid flow from the cylinder 35 and traps downstroke hydraulic pressure within the cylinder 35, so that a tight connection without play is maintained between the latch 37 and catch plate '16. Utilization of the force of gravity acting upon the crank arm 33 and the piston rod 34 also enhances the maintenance of a wedging fit of the tapered latch 37 within the tapered slot 18 of the catch plate 16.

The engaging motion of the tapered latch 37 into the catch plate 16, in response to the pressurization of the cylinder 35, is in an upward direction. This supplies a force upon the mast that is transverse to the axis of the mast pivot shaft 7, and a reaction occurs between the mast 6 and shaft 7 which holds the shaft 7 and mast 6 against one another, thereby preventing vibrations at fo r ce iszapp lied to ,the mast for holdingit in place, so

as to be integral.withgthegnachineryplatform 1, the pivot tube v33 quite 's ugly between. the bearing blocks 28, 29.-Then, shift of the'latch'37 ,withrespect flto the machinery platform '1 is minimal, so that the mast foot is held from fore and aft shift.

If angular drilling is to be performed, a modified arcuate catch plate 44, as seen in FIG. 4, having a series of tapered slots 45 formed therein for drilling at 15, 30 and 45 inclinations, is attached to the bottom of the mast 6. This arcuate catch plate 44 is stabilized by additional lattice elements 46. When the mast 6 is tilted for drilling, any one of the tapered slots 45 is aligned with the tapered latch 37, and the locking mechanism 12 is operated as described above.

It should be apparent to those skilled in the art that a number of alterations can be made without departing from the spirit of the invention. For example, a spring could be incorporated in the locking mechanism 12 which constantly biases the tapered latch 37 into a wedging position. Such feature would serve to augment gravity to safeguard the engagement of the latch 37 with the catch plate 16, or 44, should there be any loss of pressure in the cylinder 35.

In the invented device, one of the features is the positive clamping, or locking union of the mast 6 and ma chinery platform I acquired through the use of the wedging connection of the tapered latch 37 and tapered slot 18, or 45. Large magnitudes of vibratory forces occur in a drilling Operation, and it is desirable that the locking mechanism 12 maintain the wedging relationship, since the larger combined mass of the mast 6 and machinery platform I greatly reduces vibration and chatter by having a superior dampening characteristic, and by having the resonant frequency of this larger mass offset to a greater degree from the vibration frequencies created in drilling. Also, by utilizing a hydraulic cylinder 35 with the assistance of gravity to facilitate displacement of the latch 37, positive locking of the mast 6 and machinery platform 1 is assured. Further, manual handling of prior art locking pins is eliminated, and there is an accompanying reduction in labor costs and an improvement in safety factors related to mast setup.

I claim:

1. In a mast locking mechanism for a drilling apparatus having a machinery platform and a tiltable mast on the platform that turns about a pivot axis into a raised drilling position, the combination comprising:

a catch member and a latch member, one of which is mounted on said platform and the other of which is mounted on said mast, and which are brought into alignment with one another upon pivot of said mast into a raised drilling position;

an actuator for moving one of said catch and latch members into and out of engagement with the other member upon bringing said members into alignment with one another;

said catch member having a tapered slot that receives said latch member;

said latch member being tapered and having an oblique face that engages and mates with said tapered slot with a wedging fit that presents a force component transverse to said pivot axis of said mast for holding said mast in tight engagement with member intosaid engagement with said catch member said platform. in a downstroke.- 2. A mechanism as in claim 1 wherein said catch 3. A mechanism as in claim 1 wherein said actuator member is on said mast; said catch member slot Opens and the member moved thereby have a vertical compodownwardly; said latch member is pivoted on said platnent of motion whereby gravity assists movement into form and moves upward into engagement with said said wcdging fit.

catch member; and said actuator moves said latch 

1. In a mast locking mechanism for a drilling apparatus having a machinery platform and a tiltable mast on the platform that turns about a pivot axis into a raised drilling position, the combination comprising: a catch member and a latch member, one of which is mounted on said platform and the other of which is mounted on said mast, and which are brought into alignment with one another upon pivot of said mast into a raised drilling position; an actuator for moving one of said catch and latch members into and out of engagement with the other member upon bringing said members into alignment with one another; said catch member having a tapered slot that receives said latch member; said latch member being tapered and having an oblique face that engages and mates with said tapered slot with a wedging fit that presents a force component transverse to said pivot axis of said mast for holding said mast in tight engagement with said platform.
 2. A mechanism as in claim 1 wherein said catch member is on said mast; said catch member slot opens downwardly; said latch member is pivoted on said platform and moves upward into engagement with said catch member; and said actuator moves said latch member into said engagement with said catch member in a downstroke.
 3. A mechanism as in claim 1 wherein said actuator and the member moved thereby have a vertical component of motion whereby gravity assists movement into said wedging fit. 